THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

PAMELA BROWN, CNN ANCHOR: Happening now, earth-shaking explosions. A series of blasts rock a major port city with the force of an earthquake, killing dozens and injuring hundreds, including workers for an American company. Tonight, new video of the disaster, and new details of the search for the missing.

Terror leader resurfaces. A disturbing new message believed to be from the head of al Qaeda, who helped plan the 9/11 attacks with Osama bin Laden. He's now pledging allegiance to the new Taliban commander. Are they plotting together against the U.S.?

American terror targets. An apparent hit list posted by alleged ISIS hackers, containing personal information about U.S. diplomats, scientists, and military personnel, threatening to come after them and their families. What's being done to protect them?

And near disaster. A drone comes within feet of a medical helicopter transporting a patient, forcing the pilot to take evasive action. The number of similar close calls is skyrocketing. Is it only a matter of time before midair collision?

Wolf Blitzer is off today. I'm Pamela Brown. You're in THE SITUATION ROOM.

We have dramatic new video of a fiery and deadly disaster. A series of incredible explosions that ripped through one of China's biggest ports.

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: Whoa!

UNIDENTIFIED FEMALE: Oh! What the...

Holy...

UNIDENTIFIED MALE: No (EXPLETIVE DELETED) way!

UNIDENTIFIED MALE: Oh no!

(END VIDEO CLIP)

BROWN: The death toll is climbing and hundreds of people are injured, including employees of U.S.-based John Deere. It's been forced to close its plant in the area.

And we're also investigating an apparent hit list, a hit list by alleged ISIS hackers, containing sensitive and potentially dangerous personal details about more than 1,000 Americans.

We're covering all of that and more this hour with our correspondents, our expert analysts, and our guests.

And we begin with those massive explosions at one of China's biggest port cities. CNN's Will Ripley is on the scene for us at Tianjin, about 90 miles south of Beijing.

Will, what's the latest you're seeing there?

WILL RIPLEY, CNN CORRESPONDENT: Pam, we are seeing the tremendous scope of the destruction this morning. People are waking up and realizing that the damage is so extensive, pieces of the buildings are still falling off from the force of the explosion. We actually see some pieces dangling precariously overhead. The streets continue to be littered with debris.

And keep in mind, where I'm standing is well over a mile from the crash site itself -- from the blast site itself. I want to show you over there, off in the distance, that's where we saw that huge smoke plume yesterday. It appears, at least as the sun comes up, that we don't see the black smoke that we saw.

But there's still a haze over the city and concerns about the toxic air for the millions of people who have been affected by this and the thousands displaced by this massive explosion.

(BEGIN VIDEOTAPE)

RIPLEY (voice-over): Horrific video pouring in of a series of catastrophic explosions in a major Chinese port city late Wednesday. Watch this surveillance video obtained by ABC News of a man standing near the entrance of a building. The blast decimating the wall, caving in right on top of him.

The explosions felt miles away, emanating from an industrial warehouse in Tianjin, a city of 15 million two hours south of Beijing. The chemical material inside unknown and dangerous, according to Xinhua, a state-run news agency. Xinhua reporting firefighters are now suspended from tending to the billowing flames, in fear the mysterious chemicals might pose a further threat.

This as the death toll continues rising. Dozens now dead, including firefighters, and more than 500 injured.

"The house collapsed. We didn't know what happened," says one survivor.

During my live report from outside the hospital, tempers flared. A group of apparently distraught survivors, along with security officers demanding to see the pictures on my phone, forcing me off the air. Police don't stop them. Emotions running high. [17:05:04] The massive explosions equivalent to a small

earthquake, according to a China data center.

(on camera): When you look around at all the devastation here, it's really remarkable.

(voice-over): The aftermath found far and wide, buildings destroyed, and cars are completely charred more than a mile away from the blast site.

(END VIDEOTAPE)

RIPLEY: Right now people are asking exactly how could something so dangerous be allowed so close to people's homes, something that could cause this kind of damage from more than a mile away? Those are questions that people are going to continue to ask here in Tianjin.

But the big question right now, is the air safe to breathe? There are environmental monitoring stations around the city. People are very concerned that a heightened level of chemicals in the air could have serious health consequences, especially for the families here with children. And that's something that they'll be monitoring in the coming days as China tries to investigate how this happened -- Pam.

BROWN: Will Ripley, thank you so much.

We are just getting in some new video of this disaster. Ad Will Ripley showed us, it was a series of explosions, each one bigger than the last. Take a look at this.

Chinese state media is now reporting that executives of the company that own the warehouse where the explosions began have been taken into custody.

And we're also investigating a terror tape that's raising fear of a new alliance between al Qaeda and the Taliban. CNN Pentagon correspondent Barbara Starr is working this story for us.

Barbara, what are you finding out?

BARBARA STARR, CNN PENTAGON CORRESPONDENT: Good evening, Pamela. We have not heard from the head of al Qaeda in months. Now he has surfaced again, and the question is, why?

(BEGIN VIDEOTAPE)

STARR (voice-over): In an online audio message, a man purported to be al Qaeda leader Ayman al-Zawahiri pledges allegiance to the new Taliban leader Mullah Akhtar Mohammad Mansour. Hundreds in the ranks already swearing their allegiance.

GEN. RAY ODIERNO, U.S. ARMY CHIEF OF STAFF: I think, you know, with the death of Mullah Omar, the future -- it's essential (ph) to what the Taliban's going to be. I think we have to watch that very carefully.

STARR: CNN could not independently verify the authenticity of the Zawahiri message. Why would the man who succeeded Osama bin Laden pledge allegiance to the Taliban, often seen as secondary to al Qaeda?

COL. PETER MANSOOR, CNN MILITARY ANALYST: What he's doing is cementing the alliance between al Qaeda and the Taliban, an alliance that enabled al Qaeda to have a sanctuary in Afghanistan for much of the 1990s and part of the 2000s.

STARR: The Taliban had been staging massive attacks across Kabul, trying to reassert their authority and gain bargaining power in peace talks, U.S. officials believe. But Zawahiri's move may be trying to keep his al Qaeda also in play.

MANSOOR: I think it puts to rest the contention that we can somehow put the Taliban back into the power structure in Afghanistan without bringing al Qaeda back into the country.

STARR: Zawahiri and his core al Qaeda group have been locked in a battle for months over the leadership of the global jihadist movement. Zawahiri sat by bin Laden's side during the 9/11 attacks and still has not faced justice.

But now, a new, more violent generation of ISIS militants is taking center stage.

(END VIDEOTAPE)

STARR: And there are tonight still nearly 10,000 U.S. troops in Afghanistan scheduled to come out of that area at the end of next year, but they could be asked to stay if the violence grows worse -- Pamela.

BROWN: Barbara Starr, thank you so much.

And with us now in THE SITUATION ROOM, CNN counterterrorism analyst and former CIA official, Phil Mudd; our law enforcement analyst, former FBI assistant director Tom Fuentes; CNN terrorism analyst Paul Cruickshank; and CNN national security analyst Fran Townsend, who was President George W. Bush's homeland security adviser.

Paul, I'm going to start with you here. You have followed the al Qaeda leader, Ayman al-Zawahiri, extensively. Why now? Why would he decide to come out from the shadows after an unprecedented silence?

[17:10:47] PAUL CRUICKSHANK, CNN TERRORISM ANALYST: Pamela, he needed to show that he was still alive, and he's still relevant, still the leader of al Qaeda. We haven't heard from him for 11 months, almost a year, and that's a pretty unprecedented silence.

So he needed to put to bed speculation that he was dead, just like Mullah Omar -- there's been growing speculation about that. Also from within the growing jihadist movement, and that's been weakening al Qaeda at a time when it's in competition with ISIS.

And of course, there's this new leader of the Taliban now, Mullah Mansour, and he needed to come out of the woodwork to pledge allegiance to him. Otherwise the speculation would just have grown.

BROWN: And Fran, how much do you think the competition with ISIS played a role in this pledge of allegiance? What's the motivation behind it?

FRAN TOWNSEND, CNN NATIONAL SECURITY ANALYST: Oh, I think there should be no doubt. We've seen the wide recruitment efforts of ISIS, much at the expense of a Qaeda.

You know, in al Baghdadi, ISIS has a charismatic leader, having, as Paul points out, not heard from Zawahiri in 11 months. There was sort of this vacuum of leadership.

And frankly, I think the other piece of it is he wanted to cement his relationship with the Taliban. As the Taliban has become more prominently, politically. Zawahiri saw this as an opportunity to cement that alliance.

BROWN: And Zawahiri, as we know, Phil, he played a key role. He was engaged in day-to-day operations, played a key role in the planning of 9/11. Take us behind the scenes. Why haven't U.S. officials been able to get him? PHIL MUDD, CNN COUNTERTERRORISM ANALYST: To paraphrase a friend

of mine from the agency, he's still there because he's hiding. And there are four ways he hides.

The first is he's operating in areas where the U.S. doesn't have a presence. Presumably, in the Pakistani tribal area bordering Afghanistan.

Second, the Pakistanis themselves don't have a significant presence there. So they can't hunt him down.

Third is he doesn't have a digital trail. That is, he's not up on e-mail. He's not up on phone. He's not up on 21st century communications that help you target.

And fourth, you can presume he's using human couriers. That is expendable people from the local community who might do a run or two to them and then they're out of the game. So they'll go down eventually, but there are a lot of reasons why he can hide.

BROWN: But you say he doesn't have a digital trail. I'm curious, John. Could this audio message help U.S. officials track him in any way? Isn't there a courier or someone interacting with him, similar to Osama bin Laden to help track him?

TOM FUENTES, CNN LAW ENFORCEMENT ANALYST: Certainly they could, Pam, but I think the big issue here is that both the Taliban and al Qaeda, core al Qaeda, Zawahiri, see ISIS coming into Afghanistan and taking control. And then, you know, the young fighters are young and aggressive. Many of them were probably 10 years old at the time of 9/11 or the planning of 9/11. So they look at these old guys as they've been in hiding for ten years. They're cowards. They're no good.

Osama bin Laden got a lot of credit, and so he could hide. That was OK. But for Zawahiri and the rest of them, it's not OK. So they've got to come out a little bit and try to show some leadership, try to get some invigoration into the young leaders -- you know, young up and coming leaders. And they haven't done it so far.

BROWN: Phil, how much of a priority do you think it is to get him, for U.S. officials?

MUDD: Believe it or not, this would -- if I were still back in the business, this would not be my No. 1 priority. And he and bin Laden were not the No. 1 priority when I was there ten years ago.

The reason is simple. The responsibility that you have in that position is to eliminate threats and plots against New York, Washington, London, Paris. Those are typically operational commanders one level below people like Zawahiri and bin Laden. Zawahiri will not die a peaceful death. He'll go down. But he is not the same priority that you would give to someone who's actually training individuals who might be coming to a major American urban center.

BROWN: Al Qaeda still a threat. ISIS, as well. And ISIS releasing this new hit list with American names on it. We're going to talk about that. Stick around, because we have a lot more to discuss. We'll be right back.

(COMMERCIAL BREAK)

BROWN: There's a new twist in the ISIS terror threat tonight. An apparent hit list containing personal information about more than 1,000 Americans, along with a chilling threat against their lives.

[17:19:36] CNN's Brian Todd is here with all the details.

Brian, what do we know about this list?

BRIAN TODD, CNN CORRESPONDENT: Pamela, we know there are at least some legitimate personal details of U.S. military personnel and other officials on this hit list. And tonight, officials from Washington to Australia are telling us they are investigating this list, and they're warning their personnel.

(BEGIN VIDEOTAPE)

TODD (voice-over): A dry-looking spreadsheet with sensitive, potentially dangerous personal details. A group calling itself the Islamic State Hacking Division has published this list online. About 1,400 names, e-mail addresses, phone numbers and alleged passwords of U.S. military personnel and civilian government employees.

[17:20:15] At the top, a message: "O crusaders, know that we are in your e-mails and computer systems, watching and recording your every move." It says they're extracting confidential data, passing it to ISIS, and its soldiers, quote, "will strike at your necks in your own lands.

MATTHEW LEVITT, WASHINGTON INSTITUTE FOR NEAR EAST POLICY: This drives people to follow up on this information. Maybe it will get a hit on someone. Maybe it won't. It also does really freak out U.S. governments, military and law enforcement personnel.

TODD: The FBI is investigating. U.S. military and Australian police officials tell CNN they're looking into how it's affecting their people on the list.

GEN. RAYMOND ODIERNO, U.S. ARMY CHIEF OF STAFF: I take it seriously because it's clear what they're trying to do. And so it's important for us to make sure that all our force understands what they're trying to do.

TODD: Neither CNN, nor the global security firm Flashpoint Intelligence can confirm the authenticity of this claim or the accuracy of the passwords and other sensitive information on the list.

We called and e-mailed several people on the list. Some e-mails bounced back as being old addresses. Others went through. One retired serviceman confirmed to us the phone number for him on the list is accurate, and he said the Pentagon alerted him.

One Australian computer security expert says this is likely not an actual hack.

TROY HUNT, INTERNET SECURITY RESEARCHER: It's quite evident that it's an aggregation of data from multiple sources, and most of it is publicly discoverable.

TODD: But analysts say it doesn't have to be a hack of protected information. Given the recent attacks, targeting Americans in their homeland, the message to potential lone wolves is a dangerous one.

LEVITT: You can stay where you are. Do something where you are. And even if not a single one of these leads actually pans out, they are creating a sense for someone sitting in their mama's basement, you are part of us.

(END VIDEOTAPE)

TODD: A U.S. military official tells CNN following the publishing of this list, they are telling their personnel to protect their personal information, online and in social media. Don't put anything on Facebook or Twitter indicating where you are, where you work, who your relatives are, and they've had to do this before.

U.S. officials say this is at least the second time this year that a group claiming affiliation with ISIS has bragged about doing this -- Pamela.

BROWN: And Brian, there's a well-known ISIS hacker who's likely been promoting this list. Is that right?

TODD: That's right. His name is Junaid Hussein. He's a British hacker, now believed to be with ISIS in Syria. He's been hunted by coalition forces. Just after this list came out on a Twitter handle claiming to be his, there was a tweet saying, quote, "They have us on their hit list, and we have them on ours, too." That Twitter feed has since been shut down, Pamela.

BROWN: A big concern for U.S. intelligence officials. Thank you so much, Brian Todd.

And let's get more insight from our experts. Fran, I'm going to start with you again. Is this a realistic threat?

TOWNSEND: Sure it is. First and foremost, it's meant to be an intimidation tactic. Right? It's meant to strike at law enforcement and military and civilian personnel and let them know that they're not safe, regardless of where they are or their information is. So in and of itself, it's meant to be a terrorizing tactic.

I think we need to know more. That's why people are looking at was this really the result of a hack, is this an aggregation of data? Is the data accurate? All those things matter. But I will tell you, if your name is on that list, and if any of your information on it is accurate, you're very concerned tonight, as are government officials.

BROWN: And we know that the FBI is looking at this. There's been a rise in is plots in the U.S. How seriously are officials taking this threat?

CRUICKSHANK: Well, I think Fran's got it exactly right, that they have to take this threat seriously because of the threat context. These accelerating numbers of ISIS-inspired plots in the United States.

Sixteen Americans involved in those plots since March. Many of those plots are targeted at the U.S. military. That was, of course, that attack in Chattanooga just a few weeks ago. That was more like an al Qaeda-inspired plot. But there's just basically a lot of concern about this right now and also concern that Junaid Hussein, this British ISIS hacker linked to this threat, is somebody that is trying to instigate terrorist attacks in the United States and the U.K. and other western countries. He was in touch, as you reported a few months ago, with one of the attackers in that attempted attack in Garland, Texas, in May, Pamela.

BROWN: So you have someone like Junaid Hussein in touch with Americans, encouraging them to launch an attack. And you have a list with addresses of U.S. military personnel. How concerned would you need to be, Phil, if you're on that list?

MUDD: I think you have to be concerned for a few reasons. Look, in the next day or two, people will be worried about whether or not the information is accurate. I personally think that's irrelevant.

No. 1, one of the hardest things to figure out with a terror group is intent. What do they want to do? Attack an embassy? Attack a fast-food restaurant? They are indicating intent. They want you to find information on social media, for example, and go after individuals from the military, from the CIA.

The second and final reason I'd be worried is this information is readily available to a home-grown extremist. You don't have to meet with ISIS. Before I came on the show, I got on a website. Within 60 seconds, I found my home address. If you're in a position like me, you're in the former military, you have to be worried about this. It doesn't matter if the information is accurate today.

BROWN: Yes. And Tom, ISIS would like to make you think that it's a hack, but in reality, a lot of this is open source. Do you think that this is more scare tactic than anything, what ISIS is doing here?

FUENTES: Everything they say and do is a scare tactic. When they put out a global kill to all their followers or wannabe followers on a worldwide basis, that's threatening enough, except that's addressed "to whom it may concern."

Now you have an order going out, "Kill this person," and it has your name on it. I know, you know, the days even when I was a police officer in the street, we said, you know, you don't worry about the bullet with your name on it. You worry about the tens of thousands of bullets that are addressed "to whom it may concern." Well, how you have both. BROWN: I can't imagine how law enforcement has to deal with this

day in, day out. Thank you so much, Phil Mudd, Tom Fuentes, Paul Cruickshank and Fran Townsend. We appreciate it.

And coming up right here in THE SITUATION ROOM, race, justice, and the presidential campaign. Candidates caught off-guard by activists demanding change. We're taking a closer look.

(COMMERCIAL BREAK)

[17:31:00] PAMELA BROWN, CNN ANCHOR: We're following something unique in the 2016 campaign cycle. It's disrupting candidates' plans, forcing them into confrontations they'd rather avoid, and posing a threat of embarrassing them on camera. It happened to Jeb Bush last night when he was confronted by demonstrators from the Black Lives Matter movement, as we see here.

JOE JOHNS, CNN SENIOR WASHINGTON CORRESPONDENT: Pamela, the Black Lives Matter issue is just getting started, tripping up Democrats and Republicans on the trail, especially those defending their records in office. Zero tolerance policies of Martin O'Malley in Baltimore, the vote of Bernie Sanders for the crime bill in Congress, though the most visible impact right now is how it's changing the way candidates use their words.

(BEGIN VIDEOTAPE)

UNIDENTIFIED PROTESTERS: Black Lives Matter. Black Lives Matter.

JOHNS (voice-over): The chant went up at the back of the room, following a Jeb Bush campaign event in Nevada. He had already addressed the Black Lives Matter protesters by answering a question from the crowd.

JEB BUSH (R), PRESIDENTIAL CANDIDATE: These problems have gotten worse in the last few years. Communities, people no longer trust the basic institutions in our society that they need to trust.

JOHNS: But it wasn't enough to silence them. Their issue was with something he had said on the stump.

BUSH: We're so uptight and so politically correct now, you apologize for saying lives matter?

JOHNS: That was in response to an apology to the movement issued by Democrat Martin O'Malley, who said the same thing weeks ago.

JOHNS: Now candidates on both sides are choosing their words. Listen to Republican John Kasich who on CNN echoes Bush and O'Malley, but carefully.

GOV. JOHN KASICH (R), PRESIDENTIAL CANDIDATE: And all lives do matter. Black lives matter especially now because there's a fear in these communities that, you know, the justice system isn't working for them.

JOHNS: How the candidates talk about police use of force against minorities is not going away as an issue on the campaign trail or the public consciousness. It's fueled by headlines like the eruption last week in Ferguson, Missouri, on the one-year anniversary of Michael Brown's death.

Other top Democrats have heard from the movement, too, even Hillary Clinton with polls showing strong black support, was met with Black Lives Matter advocates in New Hampshire. Her husband Bill recently issued his own mea culpa for the 1994 crime bill that accelerated mass incarceration.

DAUNASIA YANCEY, FOUNDER AND LEAD ORGANIZER, BLACK LIVES MATTER BOSTON: I don't want to quote her, but she did say -- she did acknowledge that there are policies that she had been a part of promoting that have not worked.

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: That will never happen with me. I don't know if I'll do the fighting myself, or if other people will. But that was a disgrace. The way they -- I felt badly for him. But it showed that he's weak.

(END VIDEOTAPE)

JOHNS: And so how does the one African-American in the race talk about the issue? Republican Ben Carson has said police and people in black communities are often in fear of each other and the fear needs to be addressed, but what the activists say they want most from the candidates is a plan to address the issue. Though policing for the most part is a state and local issue -- Pamela.

BROWN: They are certainly making their voices heard.

Joe Johns, thank you so much.

And let's bring in Jamelle Bouie, who writes about politics, race, and justice for "Slate." CNN anchor Don Lemon, and CNN senior political reporter Nia-Malika Henderson. I want you all to stand by. We're going to talk about all of this after this quick break. [17:34:42]

(COMMERCIAL BREAK)

BROWN: Developing now, activists with the Black Lives Matter movement are confronting presidential candidates from both political parties, putting race and justice front and center in the 2016 campaign.

Nia, I'm going to start with you here. Can you set the stage for us? Who are these activists and what exactly are they trying to accomplish here?

NIA-MALIKA, CNN SENIOR POLITICAL CORRESPONDENT: Well, they really are a cross-racial group of mainly young, certainly passionate and galvanized by the string of incidents we've seen across this country, whether it's Michael Brown in Ferguson or Walter Scott in South Carolina. And they very much want to keep this in the debate. You have, from these incidents, sort of a focus on it, and then the cameras sort of go away.

[17:40:03] So they very much want to keep this in the news and they're doing it pretty effectively by crashing these events and getting these candidates to have to go on the record and address them and eventually I think the hope is that they lay out plan in terms of what they would do about what are disparities in the criminal justice system.

BROWN: Not only address them, but also even apologize in some cases. We've heard that from Martin O'Malley, Jamelle, where he has said that all lives matter, and then we heard the booing there in the crowd. Why is that so offensive to these activists?

JAMELLE BOUIE, STAFF WRITER, SLATE: I think because right now there is a particular problem of police violence against African- Americans. This problem has existed for a long time with cases like Michael Brown and Walter Scott have put it back into the news and made it -- have highlighted it for millions of Americans. And to say all lives matter in response to this particular problem doesn't really sound like you're trying to affirm the value of all lives. It sounds like you're trying to dismiss the idea of this particular problem. It's as if you're eating dinner.

BROWN: Like they're missing the point basically.

BOUIE: Right. Right.

BROWN: Of what this is all about.

BOUIE: It's as if you're eating dinner, and you're like, can I have a serving of that, and your dad says, we can all have a serving. Right? It's ignoring the actual request here. No, I want the serving of that. Not a general issue here. It's me. BROWN: But what do you say to the other side that have argued,

these other politicians, saying why are we being so politically correct here with this?

HENDERSON: Well, you know, I think Jamelle has said this before. It's almost like Black Lives Matter should have a "too" on the end of it.

BOUIE: Right.

HENDERSON: Because it really is a call for inclusion. It's a call for black lives to matter and for these politicians to look at these disparities and this idea of it, well, all lives matter sort of misses the point. That this is a very specific problem. But I do think you've had candidates comes out and say all lives matter, back up and say well, wait a minute, black lives matter, too. I believe Ben Carson was one of them who said listen, all lives matter and we shouldn't be so particular here.

But it's a divisive issue. I mean, any time I sort of tweet about this, you know, I get people sort of hash-tagging me back saying all lives matter in a way that is sort of aggressive and dismissive, I think.

BROWN: We saw even some of the protesters getting into it on both sides. Some yelling all lives matter. The other saying black lives matter.

Don, I want to bring you in on this because it has garnered a lot of attention even from Comedy Central's Larry Wilmore. And he has a lot to say about this movement. Let's take a listen.

(BEGIN VIDEO CLIP)

LARRY WILMORE, COMEDIAN: I agree that black lives matter, but black manners matter as well. All right? If we're keeping it 100. If we're keeping it 100. And also keeping it 100 based on the demographics. If Bernie Sanders' rallies were a Ben and Jerry's ice cream flavor, it would be "Nilla, please."

(END VIDEO CLIP)

BROWN: Don, your reaction there?

(LAUGHTER)

DON LEMON, CNN ANCHOR: I think if I were Larry I would have delivered that, I would have said, he would be "Nilla, please." You know, that sort of thing. But --

(LAUGHTER)

LEMON: I think that -- I think Larry makes a very good point. You know, black lives matter, yes, black lives matter. I mean, but in reality, we know -- and we understand when people say all lives matter what they mean. But we understand that the Black Lives movement, they want people to focus on black life. And what's happening with police brutality. And I applaud them. And I -- like they often get a lot of guff, the Black Lives people.

But here's what I would say to them. I think Larry is right. Black manners do matter as well. And you don't always get anything accomplished or things accomplished by shouting down the people who are on your side. Yes, Bernie could have handled it right. Yes, Martin -- differently. Yes, Martin O'Malley could have handled it differently. But if someone is in your corner and is on your side, you don't necessarily gain their support by shouting them down.

I do think that they are a political movement that has to be reckoned with in this particular election, presidential election. But they also risk becoming code pink if they don't start sitting down and talking to people and stop shouting down the very people who are on their side.

BROWN: Jamelle?

BOUIE: So in the abstract, I think Don's right. But in this particular case, six months ago, people weren't issuing out criminal justice demands. Seven months ago, they weren't. You didn't have Jeb Bush having to address this. You don't even have guys like John Kasich talking about it. Right now because of these disruptions and because of this general movement, even if it's impolite and aesthetically, you know, unpleasing for a lot of people, it has created actual concrete gains and has sort of upended the presidential race in a way that we haven't seen in a very long time. And so I would say --

LEMON: You're absolutely right. You're right. And I'm not saying that you're wrong. You're right. But at some point, you know, everyone must evolve. That's all I'm saying. I'm not saying anything bad about the Black Lives movement.

HENDERSON: And I do think social movements tend to be messy and tend to be disruptive.

LEMON: Right.

HENDERSON: I mean, the Civil Rights Movement was disruptive. The Boston Tea Party, that wasn't -- you know, it really wasn't a party. It was sort of -- you know -- you know, I mean, it was a disruptive act. And they have gotten results here. Right? I mean, they have -- Bernie Sanders has issued sort of a platform around this. He's hired African-American staffers. So they have gotten results.

BOUIE: These sort of demonstrations and confrontations. And they got an executive order of the president of the United States.

HENDERSON: That's right. And they would routinely disrupt President Obama's events. Even though they saw him as an ally, they wanted to push him much further.

BROWN: But we're seeing this as a little bit of a quandary for some of these politicians, Don. Because as we saw in the video, with Bernie Sanders, you know, the activists coming in and pushing him away, or he stepped away from the microphone, however you want to perceive it. How should these candidates handle the situation? Like a situation like this that we're watching with Bernie Sanders.

LEMON: I don't know. There are two ways of handling it, right? You can do what Bernie Sanders did, just let them talk, or you can do what Ronald Reagan did and say, you know, hey, I paid for this microphone, or you can do what Donald Trump says, which is, you know, the same as Ronald Reagan. I -- don't let them do it. But I think -- I think what you should do is, talk to the Black Lives movement people. Talk to those young people out there and listen to them.

You know, if they want to take over your microphone for a minute, you know, it may seem rude, you may be upset by it, but listen to them for a moment. And I think after a while, they may -- if you listen to them, they probably won't interrupt your event or they won't see the need to interrupt your event.

Let's hope they get to a point where that doesn't happen. But I also think that Dr. Ben Carson is right as well in that Black Lives has to go just beyond law enforcement and also deal with other issues that we face as African-Americans.

BROWN: And you mention Ben Carson. He is the only African- American candidate in the race. And he said that these activists are causing, quote, "strife," Don. Does Carson in your view have an obligation at all to embrace the Black Lives Matter movement, or is this kind of comment expected from him?

LEMON: You know, I mean, listen, he -- he can do what he wants. He doesn't have to embrace anything. I think it would be -- he would be foolish not to at least speak to them to understand what they're saying. And if he feels that there are other issues besides law enforcement issues that must be dealt within the African-American community, then he should talk to them about that. But I think it would be wise of him to meet with them and not just blow it off. I don't think -- I don't think comments like that are expected of him.

Listen, I have great respect for Dr. Ben Carson and what he's gone through and what he's achieved and what he's accomplished. I don't always agree with him. I don't always agree with any one, any one of our politicians. But I think it would be foolish of him not to meet with them and talk about what he thinks is important as well. BROWN: Interesting discussion.

And Don will be back later with his own newscast. Tune in at 10:00 p.m. eastern for "CNN TONIGHT."

Coming up right here in THE SITUATION ROOM, a deadly serious new warning sparked by an alarming spike in near collisions involving aircraft and drones.

Plus, we're bringing in amazing pictures. Take a look at the fireball from the huge blast in a major port city. We're standing by for a live update from near the blast site.

(COMMERCIAL BREAK)

[17:52:44] BROWN: We're following an urgent new warning today about the growing and potentially deadly danger posed by drones.

Let's bring in CNN aviation correspondent Rene Marsh.

Rene, what are you learning?

RENE MARSH, CNN AVIATION CORRESPONDENT: Well, Pamela, they're in the sky by the hundreds. Flying dangerously close to passenger planes. The number of close calls reported has more than doubled and tonight both the FAA and pilots are expressing concern.

(BEGIN VIDEOTAPE)

MARSH (voice-over): Tonight, the FAA is sounding the alarm about a dramatic spike in the number of close calls between planes and drones. So far this year, pilots have reported more than 650 drone sightings. Compared to 238 in all of 2014.

UNIDENTIFIED MALE: Yes, we were on the final 31 right, 800, 900 feet, was our altitude, 100 feet below us was a drone.

LES ABEND, COMMERCIAL PILOT: It absolutely is an unnecessary risk. You know, we've -- especially during the approach phase, we're busy up there in the cockpit. One of the last things we're going to expect is a drone encounter.

MARSH: Despite FAA rules that forbid flying above 400 feet near commercial planes or near an airport, hundreds and hundreds of drone operators have gone rogue.

UNIDENTIFIED MALE: Tower, we almost got hit by a drone, just to let you know up here.

MARSH: Wednesday a medical helicopter flying a patient to a hospital in Fresno, California, was forced to take evasive action after nearly crashing into a drone. Firefighters battling wildfires last month in California were forced to ground operations because of unauthorized drones. In recent weeks, drones spotted flying dangerously close to multiple jet liners flying through some of the busiest air space over New York and New Jersey.

ABEND: The FAA needs to step it up from the standpoint of certainly let's publicized to the folks that are buying this kind of equipment, this drone equipment, that there are penalties, there are fines, there's possible jail terms.

(END VIDEOTAPE)

MARSH: Well, part of the problem is anyone can buy one of these drones, online or at the mall, for a couple of hundred dollars. And they don't need any training or aviation experience to fly one. But drone lobbyists blame the FAA for the spike in close calls saying that the agency needs to get more aggressive in going after rogue operators.

[17:55:05] Now we should point out, although the FAA has said it could be catastrophic if one of those drones strikes an airplane engine or the windshield, it's worth noting no testing has been done to see exactly how much damage a drone can actually do -- Pamela.

BROWN: Very concerning stuff.

Rene Marsh, thank you so much.

And coming up, gripping new video of a fiery disaster. Huge explosions ripping through a major port city with the force of an earthquake.

(COMMERCIAL BREAK)

[18:00:00] BROWN: Happening now. Catastrophic blasts. We now have new video that captures the hellish moments as a series of explosions rip through a chemical warehouse. Tonight the death toll is climbing and millions of survivors may be at risk from toxic fumes.